what octane gas do you run in your outboard? 2024

NJfishinGuy reply :

hey just wondering what octane do you guys run in your outboard? i know my manual says no lower than 87 but would it be better with 89 or 91 or 93 octane? not sure what most people run theirs on.

Ryan

fishingfourfun reply :

Regular 87 octane

Live.2.Fish reply :

I run 87. I have heard that if you OB manual says to run 87 and you run premium (91), you can actaully gum up your motor.

GABassin reply :

I run 87 because where I live the gas is so expensive but I have ran 93 before and it felt like I had a lot better performance. I marked speed with both octanes' on the same gps and I got 4 mph faster with the same load and conditions using the 93. I have never heard that about the 93 gumming the motor either. I am not sure how it would when it is a higher quality fuel.

NJfishinGuy reply :

i think it could because it doesnt burn all the fuel off maybe... i think i might run 89 and see how she runs. not go up to 91 but not use the lowly 87 lol

guest reply :

most outboards (excluding high performance) recommend using basic 87 octane.

bassmaster8100 reply :

i run 93 just seems to run better with higher octane gas for me

RWHusker. reply :

I have ran 91 to 93 (premium) because I was told to by the service person I bought the boat from. The manual says 87. I was also told to use a $15 carbon burning additive and absolutely no ethenal. What are other thoughts.

Rod

GO BIG RED

Pa Angler reply :

Quote
Regular 87 octane

Same here that's what Mercury recommends.

Way2slow reply :

You are not doing a low compression 87 ocatane motor any good running a higher octane. Actually, just the opposite. Higher octane fuels burn slower and colder, and will cause more carbon buildup.

Some of your early 80's and almosty all 70's and older motors are a different situation. They came along long before this junk we have for gas now and most of them have too much compression to safely run todays 87 octane so I would be wise to run premium in those.

If it says 87 octane, run 87 octane unless you let your gas sit for a month or two. Gas looses octane rather quickly so if you let the boat sit for more than a month, it might pay you to add as much 93 octane as you have old gas in the tank. If for some rare occasion one of my boat sits for more than two months with gas in it, I won't run that gas, it comes out.

Pa Angler reply :

Quote
You are not doing a low compression 87 ocatane motor any good running a higher octane. Actually, just the opposite. Higher octane fuels burn slower and colder, and will cause more carbon buildup.
Some of your early 80's and almosty all 70's and older motors are a different situation. They came along long before this junk we have for gas now and most of them have too much compression to safely run todays 87 octane so I would be wise to run premium in those.

If it says 87 octane, run 87 octane unless you let your gas sit for a month or two. Gas looses octane rather quickly so if you let the boat sit for more than a month, it might pay you to add as much 93 octane as you have old gas in the tank. If for some rare occasion one of my boat sits for more than two months with gas in it, I won't run that gas, it comes out.

Your wasting gas, I guess you never heard of stabilizer I use it every winter have never had any problems.

bassmaster8100 reply :

Ive ran a little of both but 93 is whats worked best for me, my boat never sits long tho Im out every week of the year in it, if it sits for 2 weeks its a miracle, does matter to me if its 20 degrees or 120 degrees Im on the water. Water rarely freeze down here in south mississippi so I fish year around so dont have to worry about stabalizer.

Black Bass reply :

I run 89 in my '76 Evinrude 85 HP. As suggested above, being an older motor I could probably run 93 octane and gain some performance. However, because I'm cheap, 89 is my compromise.

R520dvx reply :

87 octane regular

john087 reply :

87 octane but you can always add additives to your fuel to rid the engine of carbon build up once a year, that saves you a lot of money

Way2slow reply :

Stabalizer???? The Seafoam I run also performs as a stabalizer. You can put your faith in stabalizer, you can run six month or 16 month old gas, it's your motor. As I stated, it's rare for one of mine to sit long with gas in them and that usually get used in the mower, so I wouldn't consider it wasted. I think the few gallons of gas pulled out of my tank is a lot cheaper than rebuilding a powerhead.

Keeping fresh gas is even much more critical now with the High Tech motors of today than ever before. The carb motors of a recent past time ran low compression and had a lot of cushion built in for those that think it's ok to park a boat in the fall and take it back out the next summer with the same gas in it. These newer computer controlled, DFI and four stroke motors are pushing the compression to the limit. You will can find out real quick just how expensive that few gallons of gas you didn't want to "waste" can be with those.

Redlinerobert reply :

91 octane in my Mercury Racing 300.

Pa Angler reply :

Quote
Stabalizer???? The Seafoam I run also performs as a stabalizer. You can put your faith in stabalizer, you can run six month or 16 month old gas, it's your motor. As I stated, it's rare for one of mine to sit long with gas in them and that usually get used in the mower, so I wouldn't consider it wasted. I think the few gallons of gas pulled out of my tank is a lot cheaper than rebuilding a powerhead.
Keeping fresh gas is even much more critical now with the High Tech motors of today than ever before. The carb motors of a recent past time ran low compression and had a lot of cushion built in for those that think it's ok to park a boat in the fall and take it back out the next summer with the same gas in it. These newer computer controlled, DFI and four stroke motors are pushing the compression to the limit. You will can find out real quick just how expensive that few gallons of gas you didn't want to "waste" can be with those.

6 months, 16 months I never said that but over winter it works and is recommended by the Tracker dealer for all of the Mercs including the Optimax there's a reason it's called S T A B I L I Z E R it does just that keeps the fuel from going bad for months I guess it's your choice not to believe that but it has proven itself without a doubt that it works. Didn't mean to ruffle your feathers but in PA water gets stiff and my outboard won't run on ice so that stuff has to be used I do try to run the tank down as far as I can on my last outing but I never run it empty.

striperone reply :

Way2slow hit the nail on the head in regards to octane. I don't have to add a thing to that post.

Fuel Stabilizer.

I have owned a bass boats for over 25 years. I had never added stabilizer because I would always run my boat all season long including through the winter months and not once experienced a problem. BUT, one year I didn't take the boat out during the winter, come spring the motor wouldn't run (carburated merc bridgeport) $400.00 in repairs to the gummed up fuel system put me back on the water. Not to mention that my boat was at the repair shop for over a month in the spring. So needless to say I would recommend using the stabilizer.

Jeff_NHBA reply :

87 Octane for my 02 150 XR6. No need for the high test stuff.

NJfishinGuy reply :

Quote
Stabalizer???? The Seafoam I run also performs as a stabalizer. You can put your faith in stabalizer, you can run six month or 16 month old gas, it's your motor. As I stated, it's rare for one of mine to sit long with gas in them and that usually get used in the mower, so I wouldn't consider it wasted. I think the few gallons of gas pulled out of my tank is a lot cheaper than rebuilding a powerhead.
Keeping fresh gas is even much more critical now with the High Tech motors of today than ever before. The carb motors of a recent past time ran low compression and had a lot of cushion built in for those that think it's ok to park a boat in the fall and take it back out the next summer with the same gas in it. These newer computer controlled, DFI and four stroke motors are pushing the compression to the limit. You will can find out real quick just how expensive that few gallons of gas you didn't want to "waste" can be with those.

hows the seafoam work out for ya. ive used it in my cars and it can sometimes work wonders for smoothing out a rough motor. i was thinking about running it thru my outboard. do u just run it through the gas or have u done the striaght into thr carb method

Jeff_NHBA reply :

Quote

Quote
Stabalizer???? The Seafoam I run also performs as a stabalizer. You can put your faith in stabalizer, you can run six month or 16 month old gas, it's your motor. As I stated, it's rare for one of mine to sit long with gas in them and that usually get used in the mower, so I wouldn't consider it wasted. I think the few gallons of gas pulled out of my tank is a lot cheaper than rebuilding a powerhead.
Keeping fresh gas is even much more critical now with the High Tech motors of today than ever before. The carb motors of a recent past time ran low compression and had a lot of cushion built in for those that think it's ok to park a boat in the fall and take it back out the next summer with the same gas in it. These newer computer controlled, DFI and four stroke motors are pushing the compression to the limit. You will can find out real quick just how expensive that few gallons of gas you didn't want to "waste" can be with those.

hows the seafoam work out for ya. ive used it in my cars and it can sometimes work wonders for smoothing out a rough motor. i was thinking about running it thru my outboard. do u just run it through the gas or have u done the striaght into thr carb method

Add it to the tank, just like your car.

NJfishinGuy reply :

in my car i pop off the brake booster cable and feed 1/3 can striaght into the motor and shut it down for 10 mins then start it and let it smoke out.

Way2slow reply :

I run it in the gas at 1 ounce per gallon. Every 50 hours or so I run some straight into the throttle bodies on my Ficht and straight into the carbs on the carburated motors. After running the motor with a pretty good dose having gone through them, I give one super size shot in each so it stalls the motor and let it sit overnight.

As for feathers ruffled, not mine. I only post what I do or what I would do in a similar situation and make recommendations. I could absolutely, 100%, care less what anybody else does with their equipment, that's why there are repair shops. I just base my methods on about 45 years of personal experience racing, building and modifing boats and motors and just messing with boats, and they work just fine for me.

NJfishinGuy reply :

can you give me an estimate on how much you use straight into the carbs?

Way2slow reply :

Sorry, reading my last post, I left a word out. I meant to say I run some "decarb" straight into the throttle bodies. I'm sure SeaFoam would work just fine for that also but it's not in a spray can, I buy the Johnson/Evinrude stuff that comes in the spray can. I use two cans, one can in each bank, spraying both cans at the same time going up and down the throats until cans are about 2/3 empty, then load it up with the rest until it dies.

Any brand decarb should work, I've just used the Johnson stuff for buches of years and I've never had a problem with carbon buildup.

bassassinator reply :

I have a 88 115 Murcury that still runs like a champ. While in the shop last summer for a flywheel problem, the mechanic (an old timer) advised me to burn 87 and to use Seafoam every other tank to keep the carbon from building. I really believe that it has made a difference in performance.I made sure that I added seafoam to the last tank of the season as a stabilizer. It fired right up this spring.

eulerentinc reply :

I run 87 octane in my 200 HO etec. The dealer said DO NOT run anything higher or use any additives. I'll listen to them until someone more reputable says something different.

Way2slow reply :

Etec's are a different animal. With the piston temps they run, you definetly don't want to add anything.

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what octane gas do you run in your outboard? 2024

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